Stihl 026 project saw(s)

[teacherman]

Huh?

To state in such an aggressive manner that SiC won't cut Nikasil, or hard chrome, without even checking first, makes you seem very authoritative.

Great info! Puts the two scales in perspective. Appreciate that..

I'm not sure anyone said specifically that SiC won't cut chrome....

I didnt detect any aggressiveness, but then I work in a juvie jail, so maybe I'm a wee bit desensitized...and a not so wee bit loony

I managed to scratch one up a bit with SiC paper, but it is to be a dedicated hedge trimmer saw, so I don't think it will need optimum power to run that scissors bar.

I really getta kick out of this goofy, informative, friendly, saw-crazed place called AS.......................:greenchainsaw:

 

[PES+]

I have been using sandpaper for over 30 years

I never stated that silicon carbide would not scratch anything.....and by hand it really does not do much....now what Stihl is using now for plating I don't really give a hoot about so I will put it on the table.

Do any plating cleanup BY HAND.....and choose your abrasive accordingly.

if you use acid KNOW WHAT YOU ARE DOING.....otherwise don't bother because YOU WILL WASTE MONEY

If you hit ANYTHING with ENOUGH FRICTION BAD THINGS WILL HAPPEN

That means use power tools where appropriate and do things by hand when necessary.

Simple rules of logic

If Stihl has now decided to go with too thin a plate that contains chrome IT IS NOT A HARD CHROME BORE.

FACTS

there........I feel better now

 

[PES+]

After you run the rings in on the saw walexa07 pull run a compression test and post the numbers if you would.....then pull the cylinder and snap a picture.....then and only then will you see what I mean

 

[Tazman1602]

My father picked up a nice condition 026 that had been run with straight gas. The guy brought it to the dealer, dealer tore it down and told the guy it needed new P&C, the guy didn't want to pay and told the dealer to keep the saw. My father got it for $25, no bar and chain.

He took the cylinder and cleaned it up with sandpaper to get the aluminum off the cylinder and said it looks great. I've ordered a new 44mm stihl oem piston/rings for it from ebay. The base gasket is in great shape, but do we need to replace it anyway? Anything else we need to do while it is in pieces?

He was thinking of lightly honing it with a brake cylinder hone.

I've also got an older (mid-90's) 026 purchased new that has recently gotten pretty hard to crank. It's always popped the first time in about 5 pulls, then fired right up on half choke. Now it sometimes won't crank with 30 pulls. Once running though it fires right back up fine. Does it need a carb kit and impulse line? This saw may have 30 tanks through it. Thanks in advance.

Waylan

REPLACE the base gasket -- for what it costs it will be worth it in the long run.

Just my .02 cents worth but that cylinder needs to be honed properly to remove the imbedded particles of aluminum in it. Failure to do so *could* and probably will result in the new piston failing.

I don't know Stihl saws that well, if it's a Nikasil plated cyl it *may* need to be recoated. Talking from many years of snowmobile/motorcycle hot rodding, like I said don't have much experience with Stihl.

Regards

 

[mooseman]

I will take that bet....show me proof....hard chrome plate and nikasil are harder than any paper available.....
I know tons of guys that think you can scratch glass with razor blades too.....but you can't......same principal

I never stated that silicon carbide would not scratch anything.....

 

[PES+]

Ho boy.....sandpaper is what you get at the hardware store....you can get silicon carbide paper at auto parts stores and maybe some hardware stores but it is not common.

Now....your plating is on the average .001 and many times these days less..so if you look very closely after you "scratch" this surface you will see that you have not really scratched the furface but dented the thin coating.

Have a look with a scope for your self....if you were to actually scratch the surface and tear the coating the plating will then continue to degrade.

I will shoot up a photo essay on this when I get a chance but I do not have the equipment to snap pics in through the loupe or though an angle scope.

The basis to remember is how plated or coated cylinders work....they are elastic to a much larger degree than most people realize.

I was waiting for the guy who was going to do a clean up cut of a plated cylinder to come back and tell us what he found...but he either did not attempt the cut or he decided to let it go.

If you attempt to do a clean up cut you find the the cylinder is distorted or bulged out where the larger deposits of aluminum are stuck to the bore...there are other complications in attempting to do this maneuver which are not pertinent to this discussion so I will leave those out.

Suffice it to say that when a plated cylinder is sent out for re-plating they are cut a good margin oversize first then plated back to the required bore size

Anyone who has ported a replated/coated cylinder will tell you it is much harder to cut the new coating than it is on a regular cylinder

It all comes down to this......people assume that you need to cut the entire bore evenly and get a cross hatch that looks good......cross hatch lasts about 30 seconds in a coated bore and is not necessary nor desirable as the oil retention is not in the scratches/ cross hatch but in the matrix of the coating.

Silicon carbide dingle ball hones are a disaster waiting to happen and I strongly advise not to use them......but people all decide that they are in a hurry and get the hone in the "proper" oversize of the bore....this is not a good idea and this seems to have come about by people looking at the hone manufacturer's web site in which they give and example of de-burring and smoothing the inside of an iron pipe and this iron pipe does not have any ports cut in it that I can see......nor do they make any mention of the need for bore accuracy in said pipe.

If you use a ball hone use it in a slight undersize and at slow speed in the area needed and use aluminum oxide.

You can destroy a thin chrome plate bore with an aluminum oxide ball hone by using the highest speed you can get and oversizing the hone just like the demonstration video by the heat generated by friction if you run the hone long enough and by tearing the coating at the edges of the ports which then continues in a domino like effect.

If you believe you are causing damage by hand sanding in one area I simply point out that the ball hone in reality gives no greater accuracy in regards to the cylinder roundness.

It is all relative and what you see does not always act the way you think it does.

If these coatings were so easily scratched as people seem to think.....they would be very short lived in real world use....as I have yet to see any air filter which will remove all abrasive particles which are always in the environment of a chainsaw and cut off saw.

Remember.....diamonds are cut and are the hardest substance on earth....however you will never be able to put a scratch in a diamond.

 

[mooseman]

Actually, diamonds are fractured to shape, then abraded with diamond dust...but I take your point.
I had always thought that the crosshatching was as much to help seat the rings by abrasion, as to hold oil to lube and flush the filings. If I can re-ring without honing, I would be much more likely to re-ring marginal saws. I take it that you have done this successfully in the past?

 

[PES+]

Yes.....a hard plated bore does not rely on the cross hatching to retain it's oil film.

Indeed much of the break in period on new saws is the rings wearing smooth on their face and then planishing the hone marks out of the bore to get maximum ring seal.....

The most amazing thing about plated cylinders is their apparent self healing ability provided the surface is not actually torn through or their adhesion is undermined by less than stringent applications of acids which get behind the edge of the plate and begin a flaking failure

That never ends well.

 

[teacherman]

Yes.....a hard plated bore does not rely on the cross hatching to retain it's oil film.

Indeed much of the break in period on new saws is the rings wearing smooth on their face and then planishing the hone marks out of the bore to get maximum ring seal.....

The most amazing thing about plated cylinders is their apparent self healing ability provided the surface is not actually torn through or their adhesion is undermined by less than stringent applications of acids which get behind the edge of the plate and begin a flaking failure

That never ends well.

Yes, that last part just can't be good........... but can I just put a new OEM (of course) pistin and rings in without honing out the bore? Shoot, there is SO MUCH I do not know............

 

[Lakeside53]

I'm not in total agreement with Pes about this... I do not find the flex hone to be difficult to use or damaging to cylinders. In fact. I use the often. On some really crappy cylinders with nothing to lose, I've honed them with 320 SC hones for extended periods of time, and with little to any "damage" to ports or the plating. I use a smaller sized hone (less pressure) on open ports than closed, but...

I've also never had a problem with acid and certainly not any subsequent "pealing". Most uses find it ineffective due to mix-oil saturation. I clean the cylinder in purple cleaner first, then water, then acid to remove the aluminum and then purple cleaner again to neutralize the acid. Then water to wash. Scotchbrite aggitation helps dislodge the dissolved aluminum and speed up the process.

Yes.. if the cylinder cleans up with acid and scotch brite, you can skip the hone. But... I usually give them a few second "hone" anyhow... 3-4 thou plating is what I deal with... I've given up measuring afterwards. I have the tools, but rarely see anything the disturbs me. If you want to do a relative bore measurement, run some new rings up and down the bore squarely (use the piston to push them) and measure the end gap with feeler gauges.

Maybe I dealing with better grade of cylinders? Stihl and Mahle, Nikersil and chrome...

 

[walexa07]

Are piston rings harder than the chrome plating? If not, how would they wear the crosshatch off?

Waylan

 

[mooseman]

The same way that water wears through rock, or carving wood wears down a hardened steel blade.....slowly.

 

[Freakingstang]

Are piston rings harder than the chrome plating? If not, how would they wear the crosshatch off?

Waylan

Why do they wear out then? I mean if they are harder than the chrome, why do they loose tension and need replacing?

 

[parrisw]

Why do saw chains get dull then?? Why do my table saw, skill saw, planer blades, get dull then??? Wood is much softer then the cutting tools.

 

[walexa07]

Why do saw chains get dull then?? Why do my table saw, skill saw, planer blades, get dull then??? Wood is much softer then the cutting tools.

I was posting my question to PES.........he said that aluminum oxide was softer than the chrome so it couldn't scratch it.

Waylan

 

[parrisw]

I was posting my question to PES.........he said that aluminum oxide was softer than the chrome so it couldn't scratch it.

Waylan

I know, mine wasn't meant for you, I was just being facetious.

 

[mooseman]

Relative hardness is not the only factor in dulling. The various carbides in steel are very wear resistant, but the iron substrate has plastic qualities. In clean wood, the main cause of dulling will be plastic deformation, or "edge rolling". To see this effect, take a very sharp knife and drag the edge sideways across a piece of wood. The knife will appear dull because the edge will roll over forming a hook on one side. No metal has been removed but the soft wood has dulled the hard steel. The repeated impact of the cutters with the wood has the same effect (to a much lesser degree). That is why a steeper grind angle will cut really well at first, but then dull quickly, there is not enough metal supporting the edge.
Not really what we started talking about, but just happens to be one of my areas of interest. That is likely why stihl chains stay sharp longer than oregon. They appear to be harder, but I doubt that they actually are, as too hard of a steel is susceptible to chipping. It is far more likely that it contains more or harder alloying elements like chromium or vanadium. These strengthen the metal and form carbides which resist wear (and sharpening). Also German steel is much cleaner than North American, having much less sulphur, which weakens steel. If the steel was much harder, your file would start to skip across the tooth, but stihl chain seems to wear out files faster than oregon without showing signs of skipping, which points to carbides.

 

[walexa07]

Ok,

Got the saw back together, fired up first pull, runs out good. I have a DTI 20K, what rpm should I set the saw to with a 16" B&C? Right now I have it set to 12.6K.......should it be set higher for a stock saw?

Waylan

 

[Lakeside53]

You can go to 14k without concern.

 

[stihl025]

All the debate on here about honing cylinders is making me dizzy.

Here is what I know. I just (Flex) honed an 029 cylinder that was scored (see other thread for pics). It did a great job of cleaning up the cylinder and putting the "cross hatches" on the walls. There are still scratches right below the exhaust port, but they are very fine now. It is not like a new cylinder, but I think it will be good enough to keep the saw running for a while longer. That tool definitely has a place on my work bench now.